1. Field of the Invention
The present invention relates to a video tape recorder, and more specifically, a video tape recorder which is suitable for being utilized as a watching and recording apparatus in a room or building of a bank, store or shop and etc.
2. Description of the Prior Art
In order to watch and record an inside of a room or building of a bank, store or shop and etc., a video tape recorder is utilized. In such a kind of video tape recorder, in view of a purpose thereof, it is necessary to stubbornly avoid a situation that the video record becomes disable by a failure of the recording head due to the clogging or the like.
Hitherto, a rotary head cylinder having so-called double-azimuth four-head structure is well-known. In such the double-azimuth four-head structure, as shown in FIG. 5, a head SP (+) and a head EP (+) have plus azimuth angles, respectively, and a head SP (−) and a head EP (−) have minus azimuth angles, respectively. The heads SP (+) and SP (−) are arranged back to back with an interval of 180 degrees, and the heads EP (+) and EP (−) are arranged back to back with an interval of 180 degrees. Furthermore, the heads SP (+) and EP (−) are positioned close to each other, and the heads SP (−) and EP (+) are positioned close to each other.
The heads SP (+) and SP (−) are utilized as main heads, and if the video record is performed by utilizing the subheads EP (+) and EP (−) when the clogging or the like occurs in the main heads, it is possible to continue the video record, and therefore, such the video tape recorder is useful for the watching and recording apparatus.
In reproducing by the main heads SP(+) and SP(−) the magnetic tape on which the video signal is thus recorded by using the both of the main heads and the subheads, a portion that the video signal is recorded by the main heads SP (+) and SP (−) can be reproduced well, but it is difficult to reproduce a portion that the video signal is recorded by the subheads EP (+) and EP (−) with no operation.
Therefore, it is necessary to operate the video tape recorder such that the portion that the video signal is recorded by the subheads EP (+) and EP (−) can be reproduced by using the subheads EP (+) and EP (−). In other words, there is a problem that if and when the main heads go wrong and thus the video signal is to be recorded by the subheads and the video signal recorded by the subheads is reproduced by the main heads as in a normal reproducing state after the main heads have been repaired, or in other video tape recorders having the same head structure, the video signal cannot be reproduced well.